1. Field of the Invention
The present invention relates to a pneumatic tire in which a distinguishing mark such as a character, a numeral, a symbol or a graphic is formed on a surface of a side wall portion.
2. Description of the Related Art
In general, a distinguishing mark is formed on a side wall portion of a tire. The mark is constituted by a character, a numeral, a symbol, a graphic or the like displaying a manufacturer or a type of the tire, and is provided so as to protrude from the surface of the side wall portion. A recessed portion corresponding to the mark is provided in a mold forming the tire, and the mark is formed by making rubber in the side wall portion flow into the recessed portion during cure.
There is a case that the distinguishing mark is formed by a color (for example, white) which is different from a color of a main body of the side wall portion (refer to Japanese Unexamined Patent Publication No. 9-86106), however, it is often the case that the mark is formed by a color (normally black) which is the same as the main body of the side wall portion. In such a case, particularly, since it is hard to distinguish the mark from a peripheral portion thereof, it is important to increase a visibility of the mark.
In the Japanese Unexamined Patent Publication Nos. 9-86106, 63-74703, 10-67208, and 2002-127717, there is disclosed a pneumatic tire in which a protruding portion is provided along a profile of the distinguishing mark, and it is possible to somewhat achieve an effect of emphasizing the profile of the mark so as to increase the visibility. However, in the case that the protruding portion is formed high, there is a problem that a rubber supply to a metal mold recessed portion corresponding to the protruding portion becomes short, whereby a protruding portion forming a defect called as a bare is generated, or a stress is concentrated on a root of the protruding portion and a crack is generated. Therefore, a method which can further increase the visibility of the mark while solving the above problems is desired.